Radio frequency (rf) integrated circuit (ic) packages having characteristics suitable for mass production

ABSTRACT

A radio-frequency integrated circuit chip package with N integrated aperture-coupled patch antennas, N being at least one, includes a cover portion with N generally planar patches, and a main portion coupled to the cover portion. The main portion in turn comprises at least one generally planar ground plane spaced inwardly from the N generally planar patches and substantially parallel thereto. The ground plane is formed with at least N coupling aperture slots therein. The slots are substantially opposed to the patches. The main portion also includes N feed lines spaced inwardly from the N generally planar patches and substantially parallel thereto, and at least one radio frequency chip coupled to the feed lines and the ground plane. The cover portion and the main portion cooperatively define an antenna cavity, with the N generally planar patches located in the antenna cavity. Fabrication techniques are also described. In some embodiments, N is two or more and a phased array is formed.

FIELD OF THE INVENTION

The present invention generally relates to communications circuitry,and, more particularly, to radio frequency (RF) integrated circuit (IC)packages.

BACKGROUND OF THE INVENTION

In a wireless network, the connectivity and communication betweendevices is achieved through antennas attached to receivers ortransmitters, in order to radiate the desired signals to or from otherelements of the network. In radio communication systems, such asmillimeter-wave radios, discrete components are usually assembled withlow integration levels. These systems are often assembled usingexpensive and bulky waveguides and package-level or board-levelmicrostrip structures to interconnect semiconductors and their requiredtransmitter- or receiver-antennas. With recent progress in semiconductortechnology and packaging engineering, the dimensions of these radiocommunication systems have become smaller. For applications such aswireless universal serial bus (USB), the operating distance is limitedto about a meter; and a single antenna with about 7 dBi at 60 GHz willprovide the necessary antenna gain. For distances as long as 10 meters(such as wireless video) or longer (such as radar), in point-to-pointapplications, antenna gains as high as 30 dBi, depending on theapplication, are required. However, high gain antennas for, wirelessvideo applications have very narrow beam widths, so pointing the antennais very difficult for consumers. Therefore, a radiation patternsteerable array, such as a phased array, is necessary. Phased arrays arealso widely used in military radars. However, packaging RF chips withintegrated antennas or phased arrays is extremely difficult and veryexpensive due to the expensive components and extensive labor involved.

SUMMARY OF THE INVENTION

Principles of the present invention provide techniques for implementingRF IC packages that are suitable for mass production.

In an exemplary embodiment, according to one aspect of the invention, aradio-frequency integrated circuit chip package with N integratedaperture-coupled patch antennas, N being at least one, includes a coverportion with N generally planar patches, and a main portion coupled tothe cover portion. The main portion in turn comprises at least onegenerally planar ground plane spaced inwardly from the N generallyplanar patches and substantially parallel thereto. The ground plane isformed with at least N coupling aperture slots therein. The slots aresubstantially opposed to the patches. The main portion also includes Nfeed lines spaced inwardly from the N generally planar patches andsubstantially parallel thereto, and at least one radio frequency chipcoupled to the feed lines and the ground plane. The cover portion andthe main portion cooperatively define an antenna cavity, with the Ngenerally planar patches located in the antenna cavity.

In another aspect, a method of fabricating a radio-frequency integratedcircuit chip package with N integrated aperture-coupled patch antennas,N being at least one, includes providing a cover portion and a mainportion as just described, and securing the cover portion to the mainportion.

In some embodiments of the package and the method, N is two or more, andthus, a phased array can be formed.

These and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionof illustrative embodiments thereof, which is to be read in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary embodiment of a package, in cross section,according to an aspect of the invention;

FIG. 2 shows an exemplary embodiment of another package, in crosssection, according to another aspect of the invention;

FIG. 3 shows an exemplary embodiment of yet another package, in crosssection, according to yet another aspect of the invention;

FIG. 4 is a bottom view of an exemplary package with no reflector or anembedded reflector;

FIG. 5 is a bottom view of an exemplary package with a visiblereflector;

FIG. 6 is a bottom view of an exemplary planar phased array embodiment;

FIG. 7 is a top view of a rectangular ring cavity package, according toa further aspect of the invention (please note that the terms top viewand plan view are used interchangeably herein);

FIG. 8 is a cross section taken along line VIII-VIII in FIG. 7;

FIG. 9 is a larger version of the package of FIG. 7;

FIG. 10 is a cross section taken along line X-X in FIG. 9;

FIG. 11 is a top view of a circular ring cavity package, according toyet a further aspect of the invention;

FIG. 12 is a cross section taken along line XII-XII in FIG. 11;

FIG. 13 is a smaller version of the package of FIG. 11;

FIG. 14 is a cross section taken along line XIV-XIV in FIG. 13;

FIG. 15 is a top view of an offset (side-by-side) cavity package,according to a still further aspect of the invention;

FIG. 16 is a cross section taken along line XVI-XVI in FIG. 15;

FIG. 17 is a top view of an exemplary sixteen antenna phased-arrayconfiguration, according to an even further aspect of the invention;

FIG. 18 is a top view of another exemplary sixteen antenna phased-arrayconfiguration, according to an additional aspect of the invention;

FIG. 19 is a top view of a two-part package with a cover, according toan additional aspect of the invention;

FIG. 20 is a cross section taken along line XX-XX in FIG. 19;

FIG. 21 is a top view of a two-part package similar to that of FIG. 19,but with support ridges;

FIG. 22 is a cross section taken along line XXII-XXII in FIG. 21;

FIG. 23 is a top view of a two-part package with an embedded chip,according to yet another additional aspect of the invention;

FIG. 24 is a cross section taken along line XXIV-XXIV in FIG. 23;

FIG. 25 is a top view of a different version of a two-part package withan embedded chip;

FIG. 26 is a cross section taken along line XXVI-XXVI in FIG. 25;

FIG. 27 is a top view of an LTCC-based two-part package, according tostill another additional aspect of the invention;

FIG. 28 is a cross section taken along line XXVIII-XXVIII in FIG. 27;

FIG. 29 is a top view of an exemplary two-part side-by-side package,according to an even further additional aspect of the invention;

FIG. 30 is a cross section taken along line XXX-XXX in FIG. 29;

FIG. 31 is a top view of a different version of a two-part side-by-sidepackage;

FIG. 32 is a cross section taken along line XXXII-XXXII in FIG. 31;

FIG. 33 is a top view of a package similar to FIG. 23, but with asupport ring;

FIG. 34 is a cross section taken along line XXXIV-XXXIV in FIG. 33;

FIG. 35 is a top view of an exemplary wire-bond package, according to astill further additional aspect of the invention;

FIG. 36 is a cross section taken along line XXXVI-XXXVI in FIG. 35;

FIG. 37 is a top view of an exemplary side-by-side wire-bond package,according to a still another additional aspect of the invention;

FIG. 38 is a cross section taken along line XXXVIII-XXXVIII in FIG. 37;and

FIG. 39 is a flow chart of exemplary method steps.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

One or more embodiments of the invention provide an apparatus and methodfor low cost packages with integrated antennas and phased arraysoperating in the millimeter wave (mmWave) range. An exemplary inventivepackage with integrated antennas is based on a multilayer printedcircuit board (PCB). The package contains, for example, a rectangular orring cavity for implementing high performance antenna(s) or antennaarrays and another cavity housing mmWave radio frequency (RF) integratedcircuit chips. One or more embodiments of the invention also providetechniques to overcome the difficulties in making internal cavities andto avoid the need to employ wire bond technology at mmWave frequencies.Embodiments of the inventive packaging technology are consistent withthe PCB manufacturing process and can be used for packages with anintegrated antenna or antenna array.

Instances of the invention thus provide low cost packaging withintegrated antennas or planar phased arrays; in particular, chippackaging with integrated antennas or planar phased array designs formmWave frequencies and above.

Typical chip packages with integrated antennas have three major parts:(i) an RF chip, (ii) one or more antennas, and (iii) a package carrier(and in some instances, a package lid or cover, or an encapsulant toprotect the package). One or more embodiments of the invention provide apackage that has high performance antennas, an interface forflip-chipping an RF chip and an interface for flip-chipping the packageto a printed circuit mother board.

FIG. 1 shows a cross-sectional view of an exemplary package 100,according to an aspect of the invention. Note that section lining isomitted throughout the figures, for clarity. The package has seven totallayers, including substrate and bounding layers. For mmWaveapplications, especially for frequencies above 60 GHz, bounding filmand/or layer thickness has to be considered in the design process. Giventhe teachings herein, a person having ordinary skill in the antenna andpackaging arts will know how to take the thickness into account and howto employ high precision PCB fabrication techniques to make embodimentsof the invention. The package 100 also has a number of metal layers. Inparticular, there is an outermost substrate 102. Immediately inwardtherefrom is a metal layer used for the patch(es) 104 of the patchantenna(s). Inward of the substrate 102 and patch antenna 104 (only asingle antenna is depicted in FIG. 1, but more can be provided asdiscussed below) are a bound film layer 106, another substrate layer108, and another bound film layer 109. Another metal layer, inward ofbound film 109, is used for the ground plane 110 of the patch antenna.Slot(s) 113 on the ground plane are used for the apertures of theaperture-coupled patch antennas. The ground plane 110 also separates theradiating elements (patches) 104 from the feed line(s) and the RFchip(s), discussed below.

Another substrate 112 is inward from ground plane 110. Another metallayer is inward from substrate 112 and is used to implement the antennafeed line(s) 114, pads 116, 118, 120 for RF chip connections (preferablya flip-chip/C4 (“controlled collapse chip connection”) type ofconnection), and interconnection(s) 122 (as appropriate) to one or morevias, such as via 124, in a further bound film layer 126 inward of themetal layer forming feed line 114, and a further substrate 128 inward ofbound film 126. A still further metal layer provides all the pads forsignal, control, power supply, and ground connections to the mother PCB(the mother PCB is omitted from the figure for clarity). Pads mayinclude ground pad 130 interconnected with ground plane 110 throughground via 140, as well as one or more of signal, power, and controlpads exemplified by pad 132 connected to interconnection 122 and antipad142 by via 124. The vias may be, for example, plated through holes.Package pads 134 may also be provided. Depending on the patch antennadesign, an optional reflector 144 can also be implemented on the samemetal layer as the pads 130, 132, 134. In some instances, as discussedbelow, the reflector 144 is embedded.

To implement the flip-chip approach, the chip 162 preferably has aplurality of solder dots connected directly to the chip connection pads116, 118, 120.

To enhance the patch antenna bandwidth, patches may be air suspended orsupported with a foam material with a dielectric constant close to oneat low frequency applications. However, at mmWave frequencies,especially for package applications, air suspended or foam supportedpatches are not realistic. Thus, in one or more embodiments of theinvention, an air cavity 150 can be implemented in the packages. Toavoid issues from hot gases during the PCB manufacturing process, venthole(s) 152 can be employed. These holes can be designed such that theyhave little effect on the antenna performance. For example, hole 152 canbe located near the middle of the cavity 150 or close to the edge of thecavity 150, and can be made relatively small, consistent with adequateventing. The vent holes can be on the top (outermost part of) the cavity150 as shown in FIG. 1 or on the side of the cavity as discussed below,depending on the manufacturing process used.

The ground plane 110 is also used for making ground connections throughvias (e.g., via 140) and signal, power, and control connections throughvias and antipads (e.g., via 124 with antipad 142, illustrative of a viawith antipad that could be used for signal, power, or controlfunctionality). Antipads are beneficial from a manufacturing standpoint,and result in increased reliability, as it is difficult to achievereliability in partial vias (i.e., vias such as via 124 that do notextend completely through a structure) without use of antipads.

An open chip-receiving cavity or socket 160 is realized in the substrate128 and bound film 126. This socket is used to hold the RF chip 162. Thechip is attached to the package through flip-chip bonding.

Note that all the mmWave components (antennas, power amplifiers, lownoise amplifiers, and the like) are in the package 100. Vias 124, 140are used to pass through DC or much lower frequency signals.

The package 100 may advantageously be attached to the mother board (notshown) through a ball grid array (BGA).

FIG. 2 shows an embodiment 200 substantially similar to embodiment 100except that reflector 144 is encapsulated by an additional bound layer170 inward of reflector 144 and an additional substrate 172 inward ofbound layer 170. Similar items have received the same reference numberand will not be described again. Chip receiving socket 160 is alsoformed in substrate 172 and bound layer 170 in this embodiment.

FIG. 3 shows an embodiment 300 substantially similar to embodiment 200except that vent 352 runs sideways through layer 108 so as to ventcavity 150. Similar items have received the same reference number andwill not be described again.

FIG. 4 presents a bottom view 400 where chip 162 is encapsulated withencapsulant 402. The chip can be partially or completely encapsulated,for example, for purposes of resisting humidity. A plurality of outerpads 404 may correspond, for example, to attachment, heat conduction, orground pads such as pad 130, while a plurality of inner pads 406 maycorrespond, for example, to signal, control, or power pads such as pad132. In FIG. 4, there is no reflector or the reflector is embedded. FIG.5 shows a view 500 similar to view 400 but of a package with a reflector144, such as in FIG. 1. Similar items have received the same referencenumber and will not be described again.

FIG. 6 shows an exemplary package 600 with a 2×2 planar phased arraylayout. It is possible to have more than two antennas on each row. Thisbasic 2×2 array can be used to form much larger arrays. In addition tofirst antenna patch 104 with first feed line 114, also included aresecond, third and fourth antenna patches 602, 604, 606 withcorresponding second, third and fourth feed lines 608, 610, 612. Eachfeed line is connected to chip 162 as described above. Although, forpurposes of illustrative convenience, the feed lines are shown ending atthe patches in FIG. 6, it will be appreciated that they may overlap thecorresponding patches when viewed in top or bottom plan views, and arespaced from the corresponding patch and coupling aperture when viewed incross-section as shown in FIGS. 1-3 (for example, one end of the feedline passes the center of the patch (FIG. 17) or stays at the center(FIG. 18). The other end of the feed line goes just past the edge of theRF chip).

It will thus be appreciated that aspects of the invention include apackage with a socket for an RF chip, and a planar antenna. In one ormore instances, the RF chip is flip-chip attached to the package.Internal cavities can be used to improve the patch bandwidth. Ventingholes can be used to remove the hot gases during the PCB manufacturingprocess. The package can be attached to the mother PCB through a BGA.The package can implement a planar phased array.

In view of the discussion of FIGS. 1-6, it will be appreciated that, ingeneral terms, an aperture-coupled patch antenna package, according toan aspect of the invention, can include at least one generally planarpatch, such as patch 104. Also included is at least one generally planarground plane, such as plane 110, spaced inwardly from the generallyplanar patch 104 and substantially parallel thereto. The ground plane isformed with at least one coupling aperture slot, such as slot 113,therein. The slot 113 is substantially opposed to the patch 104. Atleast one feed line, such as line 114, is spaced inwardly from theground plane 110 and is substantially parallel thereto. At least oneradio frequency chip, such as chip 162, is spaced inwardly from the feedline 114 and is coupled to the feed line 114 and the ground plane 110.Also included is a first substrate layer, such as that formed by boundfilm 126 and substrate 128, spaced inwardly from the feed line 114. Thefirst substrate layer is formed with a chip-receiving cavity, such ascavity 160. The chip 162 is located in the chip-receiving cavity 160.

Given the description herein, a person skilled in the PCB and antennaarts can make embodiments of the invention. Non-limiting examples ofmaterials that may be used include thermoset plastic/ceramic/woven glassor similar laminates such as the Rogers RO4000® series of materials (andother compatible materials) available from Rogers Corporation of Rogers,Conn. USA, as well as copper for metal layers, possibly gold-plated onpads or other exposed areas. Similar techniques can be used for all thedepicted embodiments, including FIGS. 1-18.

It will be appreciated that advantageously, embodiments of theinvention, such as 100, 200, and 300, provide a complete package and nota mere patch antenna separate from the chip and other packaging.

Note that vias such as 124, 140 may be formed, for example, using platedthrough holes.

Embodiments of the invention may also include a second substrate layer,such as that formed by substrate 108 and bound films 106, 109,interposed in a region between the ground plane 110 and a plane definedby the patch 104. The patch 104 may be advantageously formed in a firstmetal layer and the ground plane 110 may be advantageously formed in asecond metal layer.

In one or more embodiments, a third substrate layer, such as that formedby substrate 112, is interposed in a region between the ground plane 110and the feed line 114. The feed line 114 may be advantageously formed ina third metal layer. Further, one or more packages in accordance withembodiments of the invention may include at least one via, such as via190, formed in the third substrate layer 112 and coupled to the groundplane 110. A plurality of chip connection pads, such as pads 116, 118,120, can be formed in the third metal layer. At least one of the chipconnection pads, such as 118, can be coupled to the at least one via 190in the third substrate layer. The chip connection pads couple the chipto the feed line 114 (pad 120), the via 190 (pad 118) and the via 124(pad 116).

One or more embodiments of the invention may include one or more signalspads, one or more control pads, and one or more power supply pads, allof which are exemplified by pad 132, as well as one or more ground pads,such as 130. The signal, control, power supply and ground pads areadvantageously formed in a fourth metal layer. As noted, package pads134 can optionally be provided.

Also included in one or more embodiments is at least one ground via,such as 140, coupling the ground plane 110 and the ground pad 130. Theat least one ground via 140 passes through the first and third substratelayers (e g., substrate 112, bound film 126, and substrate 128), in aregion not intersecting the feed line 114. One or more embodimentsinclude at least one each of power, signal, and control antipads, suchas antipad 142, formed substantially coplanar with the ground plane 110.At least one signal via couples the signal antipad and the signal pad,and passes through the first and third substrate layers. Similarly, atleast one power via couples the power antipad and the power pad, andpasses through the first and third substrate layers. Furthermore, atleast one control via couples the control antipad and the control pad,and passes through the first and third substrate layers. As noted, pad132, via 124, and antipad 142 are illustrative of pad, via, and antipadelements that may be provided for power, signal, and controlfunctionality.

As also noted, in some instances, a reflector, such as 144, is spacedinwardly from the third substrate layer and is generally opposed to thecoupling aperture slot 113. The reflector can be located on an innersurface of the first substrate layer (e.g., inmost surface of substrate128). The reflector can be exposed, as in FIG. 1, or embedded, as inFIGS. 2 and 3, in which case the package can include a fourth substratelayer, such as that formed by bound film 170 and substrate 172, spacedinwardly from the reflector 144. The reflector can thus be embeddedbetween the first and fourth substrate layers.

Advantageously, the second substrate layer, such as that formed by films106, 109 and substrate 108, is formed with an air cavity, such as cavity150, therein. Air cavity 150 is located between the patch 104 and thecoupling aperture slot 113 in the ground plane 110. Preferably, the aircavity is formed in communication with a vent, such as vent 152 or 352.In the latter case, as in FIG. 3, the vent 352 is formed in the secondsubstrate layer; in particular, in substrate 108. In the former case,vent 152 is formed in an additional substrate layer, such as that formedby substrate 102, spaced outwardly from the patch 104. The patch isformed on the additional substrate layer 102, and the vent is formed inthe additional substrate layer 102.

As noted with regard to FIG. 6, in one or more embodiments of theinvention, two or more patches are implemented to form a planar phasedarray. Thus, in general terms, the above-discussed patch 104 may bedesignated as a first patch, and the above-discussed feed line 114 is afirst feed line. The ground plane can be formed with one or moreadditional coupling aperture slots, like slot 113. The package caninclude one or more additional generally planar patches, such as patches602, 604, 606, spaced outwardly from the ground plane. The additionalslots can be substantially opposed to the additional patches. Thepackage can also include one or more additional feed lines, such aslines 608, 610, 612, spaced inwardly from the ground plane andsubstantially parallel thereto. The at least one radio frequency chip162 is coupled to the additional feed line(s) and the first patch andadditional patch(es) are arranged to form a planar phased array. Asingle large ground plane with multiple slots can be employed in phasedarray embodiments. A phased array can include any number of patchesgreater than or equal to two; however, powers of two are advantageous,e.g., 2, 4, 8, 16, 32, and so on.

For array applications, the spacing between the antenna elements isapproximately one-half of the free space wavelength (for example, about2.5 mm at 60 GHz). Thus, it is challenging to implement multiplecavities for antennas, as the cavity wall is too thin. Embodiments ofthe invention which address this issue will be discussed with regard toFIGS. 7-18. One or more of such embodiments advantageously provide easeof fabrication in the case of arrays.

FIGS. 7 and 8 show, respectively, the top and cross-sectional views ofan exemplary package embodiment with integrated antennas. Elementssimilar to those described in the previous figures have received thesame reference character. As seen in FIG. 8, the package has the same“stackup” as the existing package in FIG. 3 (pads and vias omitted forclarity). However, there is a rectangular ring cavity 750 for allantennas, to help the antenna to have wide bandwidth and highefficiency. There is also a center island 702 to support the packagecover 102 so the cover will not sag. The island 702 is also desirable sothat the package will not deform during the attachment of chip 162. Withthis configuration, more than one antenna ring is possible (as seen inFIGS. 9 and 11.) and the antenna feed lines 114 can be very short.Island 702 can include layers 106, 108, 109, and can be formed, forexample, by milling cavity 750 into those layers. To make an island, onetypically needs to mill two times. Initially, adhere a first side “A”(say the top side) of layer 108 to a separate material C, mill half wayon second side “B” (say, the bottom side) of layer 108. Remove thematerial C from layer 108. Then, glue the layer 108 to layer 112 withlayer 109, and mill the rest of the material off from side A. FIGS. 9and 10 are similar to FIGS. 7 and 8, but with a larger cavity 750holding more antennas.

FIGS. 11 and 12 show, respectively, the top and cross-sectional views ofanother exemplary package embodiment with integrated antennas. Here, acircular ring cavity 750 is employed. Circular ring cavity 750 may, inat least some instances, be easier to manufacture (since circular shapestend to be easier to mill) than the rectangular ring cavity shown inFIGS. 7-10. Island 702 is also circular in this embodiment. FIGS. 13 and14 are similar to FIGS. 11 and 12, but with a smaller cavity 750 holdingfewer antennas. Simulations indicate that in at least some instances,circular arrays have slightly better radiation patterns than rectangulararrays.

For smaller arrays, an offset or side-by-side configuration is possible,as shown in FIGS. 15 and 16. The RF chip 162 is typically much smallerthan the antenna arrays. Thus, this configuration will not increase thepackage size much. However, the feed lines 114 will be longer than theconfigurations shown in FIGS. 7-14, and thus, the approach of FIGS. 15and 16 is advantageous for small array applications. Offsetting chip 162in cavity 160 from antenna cavity 750 prevents undesirable deflectionand stress when chip 162 is mounted in cavity 160, as the layers 102,106, 108, 109, 110, 112 above cavity 160 provide support, and thus, noisland is needed in cavity 750. The antenna radiation patterns are alsoslightly better in the offset case than the patterns for the ring cavitycase, since the array is completely filed. However, in at least someinstances, the array feed lines are more challenging to design in theoffset case, especially for larger arrays:

FIGS. 17-18 show first (receiver) and second (transmitter) sixteenantenna element phased configurations. In FIGS. 17 and 18, as in theother illustrative island embodiments, cavity 750 is defined in layers106, 108, 109, having island 1702 and outer portion 1704. For theconfigurations in FIGS. 17 and 18, the package size is only 28 mm×28 mm,with a 46 mil height (into the page) (Note 46 mil=0.046 inches=1.17 mm).In FIG. 17, the RF chip 162 requires coplanar waveguide (CPW) feedantennas so there are sixteen microstrip to CPW transitions 1902. Chip162 resides in chip cavity 160. (Note also feed lines 114, reflectors144, and ground plane slots 113.) The configuration of FIG. 17 employsone ground plane slot per patch, while that in FIG. 18 employs twoground plane slots 113 per patch 104. Note also FIGS. 17 and 18 are topviews where dashed (hidden) lines are not used, for illustrativeconvenience—chip 162 in cavity 160 is located below island 1702, just asin FIGS. 7-14.

One or more embodiments of the invention thus provide a package with asocket 160 for an RF chip 162, and an internal cavity 750 for planarantenna arrays. The antenna cavity 750 can be, for example, a circularor rectangular ring, or a large cavity for side-by-side configurations(an example of the latter is shown in FIGS. 15 and 16). Embodiments ofthe package can implement a planar phased array, preferably without theneed for vias for RF feed, and in one or more embodiments, with asubstantially equal, and relatively short, feed line length. If arelative larger phased array is required, more antenna elements can beused by enlarging the cavity size, as shown in FIGS. 9-12.

In view of the description of FIGS. 7-18, it will be appreciated that,in general terms, a radio-frequency integrated circuit chip package withN integrated aperture-coupled patch antennas, N being at least two,includes N generally planar patches 104, as well as at least onegenerally planar ground plane 110 spaced inwardly from the N generallyplanar patches and substantially parallel thereto. The ground plane isformed with N coupling aperture slots 113 therein, and the slots aresubstantially opposed to the patches 104 (in some instances, such asFIG. 18, there may be more than N slots—for example, 2N slots, two slotsfor each patch). N feed lines 114 are spaced inwardly from the groundplane 110 and substantially parallel thereto. At least one radiofrequency chip 162 is spaced inwardly from the feed lines 114 andcoupled to the feed lines 114 and the ground plane 110. Note that vias,pads, and anti-pads as described with respect to FIGS. 1-6 can also beused in the embodiments of FIGS, 7-18. The N patches 104 can be arrangedto form a planar phased array.

A first substrate layer, such as that formed by bound film 126 andsubstrate 128, is spaced inwardly from the feed lines 114, and is formedwith a chip-receiving cavity 160, with the chip 162 being located in thechip-receiving cavity. A second substrate layer, such as that formed byfilms 106, 109 and substrate 108, is interposed in a region between theground plane 110 and a plane defined by the patches 104. The patches 104are formed in a first metal layer, the ground plane 110 is formed in asecond metal layer, and the second substrate layer defines an antennacavity 750, with the N generally planar patches 104 being located in theantenna cavity 750.

In some instances, an island 702, 1702 is formed in the second substratelayer, within the cavity 750, thus defining a ring shape of the cavity,and the N generally planar patches 104 are located in the ring shape,with the island 702, 1702 being substantially opposed to thechip-receiving cavity 160. “Substantially opposed,” as used herein, isintended to describe a configuration where the island at least partiallyoverlaps the chip-receiving cavity when viewed in plan, to help supportinsertion loads from insertion of chip 162 into cavity 160. The islandand the cavity may have a variety of shapes, and may have the same ordifferent shapes in any particular instance. In some exemplary,non-limiting cases, both are substantially rectangular (rectangularencompassing, but not limited to, square) when viewed in plan, while inother, exemplary, non-limiting cases, both are substantially circularwhen viewed in plan.

In some instances, a third substrate layer, such as that formed bysubstrate 112, is interposed in a region between the ground plane 110and the feed lines 114, and the feed lines 114 are formed in a thirdmetal layer. In one or more embodiments, N reflectors 144 are spacedinwardly from the third substrate layer and generally opposed to thecoupling aperture slots 113. The reflectors 144 can be located, forexample, on an inner surface of the first substrate layer. Furthermore,in some instances, a fourth substrate layer, such as that formed bybound film 170 and substrate 172, is spaced inwardly from the reflectors144, with the reflectors 144 being embedded between the first and fourthsubstrate layers.

In other instances, such as shown in FIGS. 15 and 16, the antenna cavity750 is spaced away from the chip-receiving cavity 160 when viewed inplan, such that loads incurred during insertion of the chip 162 into thechip-receiving cavity 160 are substantially supported away from theantenna cavity (for example, by compression in the layers 102, 108, 106,109, 110, 112 immediately over chip 162).

In some instances, a cover, such as layer 102, is secured over theantenna cavity 750, and is at least partially supported by the island702.

In another aspect, a method of fabricating a radio-frequency integratedcircuit chip package of the kind described includes providing a packageof the kind described, without the chip 162 inserted, and with theisland 702 as described, as well as inserting at least one radiofrequency chip 162 into the cavity 160, with the island 702 supportingloads induced by the insertion of the chip into the cavity.

In yet another aspect, a method of fabricating a radio-frequencyintegrated circuit chip package of the kind described includes providinga package of the kind described, without the chip 162 inserted, and withthe antenna cavity spaced away from the chip-receiving cavity whenviewed in plan (as shown, for example, in FIGS. 15 and 16), as well asinserting at least one radio frequency chip 162 into the cavity 160,such that loads incurred during insertion of the chip 162 into thechip-receiving cavity 160 are substantially supported away from theantenna cavity (for example, by compression in the layers 102, 108, 106,109, 110, 112 immediately over chip 162).

Internal cavities can be produced in PCB-based packages, as describedabove, but may involve some challenging processes. Internal cavities arevery difficult to implement in the low temperature co-fired ceramic(LTCC) process. To address these issues, additional aspects of theinvention will now be described. Thus the package design can beimplemented in both PCB and LTCC processes. In one or more embodiments,the package can be split into two parts: a main part and a cover.

Aspects of the invention provide an apparatus and method for low costpackages with integrated antennas and phased arrays, operating in themillimeter wave (mmWave) range. One or more embodiments of a packagewith integrated antennas are based on multilayer PCB or LTCC, andinclude a rectangular or ring cavity for implementing high performanceantenna arrays and another cavity for housing mmWave RF chips. In one ormore embodiments, the internal cavity is avoided by splitting thepackage into two parts: a main body and a cover. This approach isconsistent with the PCB and LTCC manufacturing processes and can be usedfor packages with an integrated antenna or antenna array. Further, thisapproach is suitable for automatic processes and reduces the number ofcomponents involved with packaging antennas. The “splitting” approachrelates generally to low cost packaging with integrated antennas orplanar phased arrays, and to chip packaging with integrated antennas orplanar phased array designs for mmWave frequencies and above.

Thus, in the “flipping” approach, the embedded (internal)-cavity becomesan open cavity. FIGS. 19 and 20 show top and sectional views of a first“splitting” embodiment. This embodiment is similar to that of FIGS. 13and 14, except that layers 106 and 102 are omitted, and cover 2102 ispresent. The embodiment of FIGS. 21 and 22 is similar to that of FIGS.19 and 20, except that ridges 2150 are provided to support island 702.For the structures in FIGS. 19-22, the opened cavity 750 is positionedin the “main” (lower) part, as opposed to the cover 2102, since the chip162 preferably should have back support.

The embodiment of FIGS. 23 and 24 is somewhat similar to that of FIGS. 7and 8, except that the “splitting” approach is employed, such that cover2102 is employed and layer 106 is omitted, and the chip 162 is locatedwithin cavity 750 instead of region 160 as in FIG. 8. Attendant changesare made in the feed line 2414, which is located on an upper surface oflayer 112, and in the ground plane 2410 (with slots, not separatelynumbered), which is located between layers 112, 126. Ground vias 2462,2464 are provided to make an external ground terminal available (via2462) and to ground chip 162 to ground plane 2410. One or moreadditional vias 2460 can be provided for signals, power, and/or controlpurposes. The embodiment of FIGS. 25 and 26 is similar to that of FIGS.23 and 24, except that in this case cavity 750 is essentially formed inthe cover portion, as layers 2606, 2608 are provided on cover portion2602. For the structures in FIGS. 23-26, the open cavity 750 can eithergo to the main part, as in FIGS. 23 and 24, or the cover part, as inFIGS. 25 and 26 (since chip 162 is present in cavity 750). In any of the“split” embodiments, the two parts (cover portion and main portion) canbe fastened, for example, by gluing together or flip-chipping together,as known to the skilled artisan from B. Min and G. M. Rebeiz, “ALow-Loss Silicon-on-Silicon DC-110-GHz Resonance-Free Package,” IEEETrans. on Microwave Theory and Techniques, Vol 54, NO. 2, pp. 710-716,February 2006.

Additional manufacturing steps are needed to make the island 702. Toreduce the steps, ridges 2150 can be used as shown in FIGS. 21-22. Byway of clarification, the island is an isolated part. If one mills layer108, it will fall off or move. That is why it is hard to make. If ridgesare used the “island” is attached to the other part of layer 108. Somilling is much easier.

The antennas in FIGS. 19-22 function similarly to those described above.The embodiments in FIGS. 23-26 have certain significant differences. Thechip 162 is completely inside the package, so it is fully protected. Adifferent aperture-coupled patch antenna is employed; as alluded to inthe description of FIG. 24, the feed lines 2414 are between the patch104 and the ground plane 2410. This is possible since reflectors 144 areused. Further, the embodiments of FIGS. 23-26 are particularlyadvantageous for mass production, since different via structures areused, as described with regard to FIG. 24.

Adhesive layers, such as layers 170, 126, 2606, in FIG. 26, maytypically be employed for embodiments using PCB manufacturingtechniques. In another approach, shown in FIGS. 27 and 28, LTCCmanufacturing techniques are employed, and the adhesive layers are notneeded.

FIGS. 31 and 32 show top and sectional views of a side-by-side“splitting” embodiment. This embodiment is similar to that of FIGS. 15and 16, except that layers 106 and 102 are omitted, and cover 3202 ispresent. The embodiment of FIGS. 29 and 30 are similar to FIGS. 31 and32, except that in this case cavity 750 is essentially formed in thecover portion, as layers 3006, 3008 are provided on cover portion 3202;furthermore, chip 162 is in cavity 750, vias 2460, 2462, and 2464 areprovided as described with respect to FIG. 24, and the feed line 2414 islocated between patches 104 and ground plane 2410, with use ofreflectors 144, as described above with respect to FIG. 24.

In embodiments such as those of FIGS. 23-28, the RF chip 162 can providesome support to the package cover. However, this puts some limits on theantenna cavity design, and the chip support for the cover might not besufficient if a larger array is required. In this case, a ring support3370 to the cover might be advantageous, as shown in FIGS. 33-34, whichare otherwise similar to FIGS. 25 and 26. Ring support 3370 can beformed, for example, in layers 2606, 2608. Ridges similar to ridges 2150can optionally be employed with ring support 3370 (not shown in FIGS. 33and 34), to make manufacturing more easy, as described above.

In a number of exemplary embodiments described above, the chip 162 isflip-chip attached to the package. The flip-chip attachment providesgood interconnection performance. However, flip-chip process may, atleast in some circumstances, cost more than the wirebonding process.FIGS. 35 and 36 show an embodiment with wire bonds 3682 to interconnectchip 162 with feed lines 2414. Chip 162 is present in a cavity (notseparately numbered) in a lower portion 3680, which may have, forexample, two layers due to the reflector 144. Vias are omitted from FIG.36 for clarity. FIGS. 37 and 38 show a wire-bonded side-by-sideembodiment, with wire bonds 3890 to interconnect chip 162 to via 2460;wire bond 3892 to interconnect chip 162 with via 2462; and wire bond3894 to interconnect chip 162 with feed line 2414.

One or more embodiments thus provide ridged structures, such as 2150,that can be used to remove the center island (that is, the structure isno longer an island since it is connected to other parts). Furthermore,in some embodiments, such as in FIGS. 24, 26, 28, 30, 34, 36, and 38,the feed line can be between the patch and the ground plane. Yetfurther, some embodiments provide a two-part structure that allows thechip to be wirebonded to the package, as in FIGS. 36 and 38, and/or atwo-part structure with the chip embedded inside the package, as inFIGS. 24, 26, 28, 30, 34, 36, 38.

Thus, one or more embodiments of a radio-frequency integrated circuitchip package with N integrated aperture-coupled patch antennas, N beingat least one, include a cover portion 2102, 2602, 3202, with N generallyplanar patches; and a main portion (lower stackup in FIGS. 20, 22, 24,26, 28, 30, 32, 34, 36,. and 38) coupled to the cover portion. The mainportion includes at least one generally planar ground plane 110, 2410spaced inwardly from the N generally planar patches 104 andsubstantially parallel thereto. The ground plane is formed with at leastN coupling aperture slots therein, the slots being substantially opposedto the patches. The main portion also includes N feed lines 114, 2414spaced inwardly from the N generally planar patches and substantiallyparallel thereto, and at least one radio frequency chip 162 coupled tothe feed lines and the ground plane. The cover portion and the mainportion cooperatively define an antenna cavity 750. The N generallyplanar patches 104 are located in the antenna cavity.

In some cases, such as FIGS. 24, 26, 28, 30, and 34, the chip is locatedin the antenna cavity, and the feed lines 2414 are located outwardly ofthe ground plane 2410. This is enabled by N reflectors 144 spacedinwardly from the ground plane and the feed lines and generally opposedto the coupling aperture slots. This approach can also be used inwire-bond embodiments of FIGS. 36 and 38, wherein chip 162 may belocated in an outward-facing cavity in the main portion.

In some cases, the main portion has a first substrate layer, asdiscussed above, spaced inwardly from the feed lines 114, and the firstsubstrate layer is formed with a chip-receiving cavity 160, the chipbeing located in the chip-receiving cavity. In this case, the feed lines114 are located inwardly of the ground plane 110. An island 702 can beformed within the antenna cavity, thus defining a ring shape of thecavity, the island being substantially opposed to the chip-receivingcavity. The island and/or cavity can be round, rectangular, or any otherdesirable shape consistent with manufacturability. One or more islandsupport ridges 2150 can be located within the cavity.

In the case where the feed lines are inward from the ground plane,optionally, N reflectors 144 can be spaced inwardly from the groundplane and the feed lines and generally opposed to the coupling apertureslots.

As in FIGS. 26, 28, 30, 34, 36, and 38, in some instances, the coverportion is formed with inward projections to define the antenna cavity.Optionally, the cover portion can be formed with an inward-projectingring support 3370. As in FIGS. 20, 22, 24, and 32, in other instances,the main portion is formed with outward projections to define theantenna cavity.

In some embodiments of the package, N is two or more. The N patches canbe arranged to form a planar phased array.

As shown in FIGS. 30, 32, and 38, in some cases, the antenna cavity isspaced away from the chip-receiving cavity when viewed in plan. Forexample, in the embodiment of FIG. 32, loads incurred during insertionof the chip into the chip-receiving cavity are substantially supportedaway from the antenna cavity.

In another aspect, with reference to FIG. 39, an exemplary method 3900of fabricating a radio-frequency integrated circuit chip package with Nintegrated aperture-coupled patch antennas, N being at least one, isdescribed. After beginning at step 3902, steps 3904 and 3906 includeproviding a cover portion and a main portion as described, and step 3910includes securing the cover portion to the main portion. In embodimentswhere the chip is located in the antenna cavity, an additional stepincludes locating the chip in the antenna cavity, while in embodimentswhere the chip is located in a chip-receiving cavity, an additional stepincludes locating the chip in the chip-receiving cavity—both thesepossibilities are represented in the flow chart by step 3908. Inembodiments using the island, where significant loads are anticipatedduring chip location, an additional step includes supporting, with theisland, insertion loads associated with the location of the chip, as perthe parenthetic in block 3908. Main portions and/or cover portions maybe formed, for example, using printed circuit board techniques and/orco-fired ceramic techniques, as indicated by the parenthetic expressionsin blocks 3904 and 3906—in other instances, these items could beobtained from elsewhere and assembled by an entity other than the entitythat assembles them. The chip can be attached, for example, usingflip-chip techniques or wire bond techniques. The method continues atblock 3912 (for example, one could stop or fabricate more packages).Again, in some embodiments of the method, N is two or more. The Npatches can be arranged to form a planar phased array.

Note that, to avoid clutter and confusion, use of hidden (dashed) linesis generally avoided in the top (plan) views herein.

It will be appreciated and should be understood that the exemplaryembodiments of the invention described above can be implemented in anumber of different fashions. Given the teachings of the inventionprovided herein, one of ordinary skill in the related art will be ableto contemplate other implementations of the invention.

Although illustrative embodiments of the present invention have beendescribed herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments, and that various other changes and modifications may bemade by one skilled in the art without departing from the scope ofspirit of the invention.

1. A radio-frequency integrated circuit chip package with N integratedaperture-coupled patch antennas, N being at least one, said packagecomprising: a cover portion with N generally planar patches; and a mainportion coupled to said cover portion, said main portion in turncomprising: at least one generally planar ground plane spaced inwardlyfrom said N generally planar patches and substantially parallel thereto,said ground plane being formed with at least N coupling aperture slotstherein, said slots being substantially opposed to said patches; N feedlines spaced inwardly from said N generally planar patches andsubstantially parallel thereto; and at least one radio frequency chipcoupled to said feed lines and said ground plane; wherein said coverportion and said main portion cooperatively define an antenna cavity,said N generally planar patches being located in said antenna cavity. 2.The package of claim 1, wherein N is at least two.
 3. The package ofclaim 2, wherein said feed lines are located outwardly of said groundplane, further comprising N reflectors spaced inwardly from said groundplane and said feed lines and generally opposed to said couplingaperture slots.
 4. The package of claim 3, wherein said chip is locatedin said antenna cavity.
 5. The package of claim 2, wherein: said mainportion further comprises a first substrate layer spaced inwardly fromsaid feed lines, said first substrate layer being formed with achip-receiving cavity, said chip being located in said chip-receivingcavity; and said feed lines are located inwardly of said ground plane.6. The package of claim 5, further comprising an island formed withinsaid antenna cavity, thus defining a ring shape of said cavity, saidisland being substantially opposed to said chip-receiving cavity.
 7. Thepackage of claim 5, wherein said island and said antenna cavity aresubstantially rectangular when viewed in plan.
 8. The package of claim5, wherein said island and said antenna cavity are substantiallycircular when viewed in plan.
 9. The package of claim 5, furthercomprising at least one island support ridge located within said cavity.10. The package of claim 5, further comprising N reflectors spacedinwardly from said ground plane and said feed lines and generallyopposed to said coupling aperture slots.
 11. The package of claim 2,wherein said cover portion is formed with inward projections to definesaid antenna cavity.
 12. The package of claim 11, wherein said coverportion is formed with an inward-projecting ring support.
 13. Thepackage of claim 2, wherein said main portion is formed with outwardprojections to define said antenna cavity.
 14. The package of claim 2,wherein said N patches are arranged to form a planar phased array. 15.The package of claim 2, wherein said antenna cavity is spaced away fromsaid chip-receiving cavity when viewed in plan, such that loads incurredduring insertion of said chip into said chip-receiving cavity aresubstantially supported away from said antenna cavity.
 16. A method offabricating a radio-frequency integrated circuit chip package with Nintegrated aperture-coupled patch antennas, N being at least one, saidmethod comprising the steps of: providing a cover portion with Ngenerally planar patches; providing a main portion comprising: at leastone generally planar ground plane, said ground plane being formed withat least N coupling aperture slots therein; N feed lines; and at leastone radio frequency chip coupled to said feed lines and said groundplane; and securing said cover portion to said main portion; wherein:said cover portion and said main portion cooperatively define an antennacavity, said N generally planar patches being located in said antennacavity; said ground plane is spaced inwardly from said N generallyplanar patches and substantially parallel thereto; said slots aresubstantially opposed to said patches; and said N feed lines are spacedinwardly from said N generally planar patches and substantially parallelthereto.
 17. The method of claim 16, wherein N is at least two.
 18. Themethod of claim 17, wherein: said feed lines are located outwardly ofsaid ground plane; and said main portion further comprises N reflectorsspaced inwardly from said ground plane and said feed lines and generallyopposed to said coupling aperture slots; further comprising theadditional step of locating said chip in said antenna cavity.
 19. Themethod of claim 17, wherein: said main portion further comprises a firstsubstrate layer spaced inwardly from said feed lines, said firstsubstrate layer being formed with a chip-receiving cavity; and said feedlines are located inwardly of said ground plane; further comprising theadditional step of locating said chip in said chip-receiving cavity. 20.The method of claim 19, wherein at least one of said cover portion andsaid main portion further comprises an island formed within said antennacavity, thus defining a ring shape of said cavity, said island beingsubstantially opposed to said chip-receiving cavity, further comprisingthe additional step of supporting, with said island, insertion loadsassociated with said location of said chip.
 21. The method of claim 17,further comprising the additional step of forming at least said mainportion using printed circuit board techniques.
 22. The method of claim17, further comprising the additional step of forming at least said mainportion using low temperature co-fired ceramic techniques.
 23. Themethod of claim 17, further comprising coupling said chip using one offlip-chip techniques and wire bond techniques.